Aluminum-containing copper-base bearing metal



Patented Dec. 27, 1949 'AIiUMINUM-CONTAINING COPPER-BASE BEARING METAL Harry P. Croft.Cleveland Heights, and Edward J. Dunn, Euclid, Ohio, assignors to Chase Brass & Copper 00. Incorporated, Waterbury, Conn.,

a corporation of Connecticut No Drawing.

Application February 6, 1947,

Serial No. 726,972

' 4 Claims. (01. 75-1575) The present invention relates in general to copper-base alloys and, more especially, to an improved bearing metal formed of a copperbase alloy.

It is an object of the'invention toproduce an inexpensive copper-base bearing metal having high wear-resistance.

A still further object of the invention is to produce a superior bearing metal comprising a copper-base alloy. which utilizes aluminum as one of its constituents. I I

With the above and other objects in view, as will appear to those skilled in the art from the present disclosure, this invention includes all features in the said disclosure which are novel over the prior art.

In order that the invention may be more fully appreciated, it should be pointed out that copperbase alloys have been used extensively for bearing metals, but that prior to the discovery which characterizes the present'inverition, copper-base bearing alloys have consisted in general of a preponderant amount of copper in combination with suitable amounts of tin, lead and zinc. The inclusion of tin has been considered essential to the success of the copper-base bearing metal, hereinafter referred to as a tin-containing copper-base bearing metal. Recently, however, and more particularly during the war years, the scarcity of tin and its high cost greatly curtailed the manufacture of tin-containing copperbase bearing metals.

The present invention contemplates an alloy which is suitable for bearings, bushings and the like, and comprises a copper-base alloy which does not use any appreciable amount of tin, i. e., is substantially tin-free but which, in addition to the preponderance of copper, includes suitable amounts of lead, aluminum and zinc in substantially the following proportions: aluminum about 4%, lead about 4% and zinc about 4%, the copper comprising substantially the balance. The terms substantially the balance or a balance substantially of copper shall be understood to mean either pure copper or copper with other innocuous ingredients in such small amounts and of such physical characteristics as not to seriously interfere with the superior performance of the aluminum-containing copper-base bearing metal.

The foregoing percentages insure a superior bearing metal but it will be understood that the wear-resistance characteristics of the aluminumcontaining copper-base bearing metal will not be seriously impaired by slight variations of these amounts. Thus, the aluminum may be present in amounts fromas low as about 3% to as high as about 5%. Similarly, lead may be present in amounts from as low as 3% to as high as about 5%, and zinc may be present in amounts from as low as about 2 7 to as high as about 4 /2, the balance being copper in each of the foregoing instances.

A' series of tests of'an aluminum-containing copper-base bearing metal having substantially the above analysis and hereinafter referred to as an aluminum-containing bearing metal," were run to determine the performance of the alumnium-containing bearing metal when used as the bushing of a piston. For the purposes of comparison, two tin-containing copper base bushings were tested at the same time and under identical conditions. The principal conditions of the tests were as follows:

(1) Speed-31.50 R. P. M. (60 miles per hour). (2) Load-30 HP (correspond to normal road load at 60 miles per hour). (3) Jacket temperature a. Inletl90 F. b. Outlet-200 F. (4) Oil sump temperature--280 F. (5) Air. fuel ratio-14% to 1.

Bushing Material Composition Time Wear Hours Inches Alum num-containing 88% Cu, 4% Al, 4% 720 0.00025 beanngmetal. P n.

Tin-ctoilltaining bearing 88% Cu, 4% Sn, 4% 720 0.0014

me a n.

Tin-containing bearing 011% 5% Sn, 9% 360 0.0006

metal. Pb, 1% Zn.

Because of the very nature of aluminum, it might be presumed, reasonably, that its use as an ingredient of a copper-base alloy for a bearing metal would not effect any unusual results. Consequently, the discovery that an aluminum-containing copper-base bearing metal has a wearresistance not only equal to but substantially twice that of the tin-containing copper-base bearing metals heretofore used, was wholly unexpected and constitutes an invaluable contribution to the art.

The aluminum-containing bearing metal of this invention may be made by any of the well known methods-now employed in making copperbase alloys asior-instance, by melting the copper to substantially 2200 F. and then adding the lead, aluminum and zinc in turn, the melt being covered with charcoal throughout the operation. After the several ingredients of the alloy have been added, the melt is held at a final heat for substantially five minutes, after which it is poured into suitable molds.

The molded bars may thenbe subjected to a suitable rolling schedule, by well known techniques, for reducing the bars to relatively-thin wrought sheet-metal stock suitable for bushings. For example, the molded bar stock may be passed successively through rolls to reduce its original diameter of substantially 1.255 inches to about 0.790 inch:and,"thereafter, the wrought-metal is adapted to be annealed and rolled successively until it is reduced 'tosubstantially 0.225 inch. The foregoing description of the treatment of the aluminum-containing copper-base alloy for forming wrought bushings is by way of illustration only and it 'will be understood that the specific treatment .of the alloy will vary in accordance with well known practices and the results to be ob- "tained.

Although reference has been made above to aluminum-containing copper-base bearing metals having specific compositions, it is to be understood that the invention is not limited to the proportions'reoited, but is inclusive of all proportions within the scope-of the appended claims.

The invention maybe carried out in other specific ways thanthose herein set forth without departing from the spirit and essential characteristics of :the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

We claim:

1. A copper-base bearing metal comprising not less than 3% to as high as 5% aluminum, from 2.5% to 4.5% zinc and from 3 to 5% lead, and the balance-copper.

2. A tin-free copper-base bearing metal consisting of the elements aluminum, zinc, lead and copper in the proportions of substantially 4% aluminum, substantially 4% zinc and substantiall 4% lead, and the balance copper.

'3. A hearing metal comprising a substantially tin-free copper base alloy containing not less Ithanl3% to as high as 5% aluminum, from 2.5% to 4.5% zinc and from 3% to 5% lead, the balance being copper.

4. A bearing metal comprising a wrought substantially tin-free copper base alloy consisting of the elements "aluminum, zincylead and copper in the proportions of substantially 4% aluminum, substantially 4% zinc and substantially 4% lead, the balance being copper.

' HARRY 'P. CROFT. EDWARD J. DUNN,

REFERENCES CITED The following references are of record in the file of this patent:

UNITEDJSTATES PATEN TS Number Name Date 1,468,828 Najacht Sept. 25, 1923 2,195,434 Silliman Apr. 2, 1940 "OTHER REFERENCES Metals .I-Ia-nd-book, 1939 ed.,=published by the American Society for Metals, page 1457. 

